Because of excellent in properties such as mechanical strength (especially, impact-resistant properties), electrical properties, transparency etc., polycarbonate resins have been widely used as engineering plastics in various sectors such as office automation equipment, electrical and electronic equipment, automobiles, etc. Recently, in the field of liquid-crystal displays, high reflectance materials made of polycarbonate resins increasingly have greater use in backlight application. Among others, application to monitors and televisions is remarkable, and enlargement of a backlight member is increasingly in progress as the display size is becoming larger. Accordingly, as parts of the backlight member such as a reflecting plate, a reflecting frame, a cold cathode-ray tube supporter etc. are becoming lager and the residence time during molding is becoming longer, there is a tendency that thermal stability in residence under harder molding conditions than with conventional conditions is desired. In addition, since manufacturing abroad has become frequent due to globalization in recent years, a material having a wide range of manufacturing conditions is increasingly desired, wherein the material can provide good products regardless of the level of skills or the level of perfection of molding techniques or molding machines.
On the other hand, in order to provide a reflecting function, incorporation of titanium oxide into polycarbonate-type resins or polyester-type resins has been conventionally performed. In such a case, methods for improving the thermal stability in residence have been generally adopted, for example, to prevent hydrolysis reaction between the polycarbonate resins and titanium oxide by using a method such as coating titanium oxide with a reactive silicone in advance. However, there was a problem, that is, when the amount of titanium oxide was increased in order to improve the reflectance of the composition, the thermal stability in residence during molding became increasingly poor, resulting in the reduction of the reflectance and appearance of the molded object, and hence it was generally difficult to make high reflectance and the thermal stability in residence during molding compatible with each other.
Further, there is disclosed a resin composition wherein an inorganic filler whose base amount is 20 μmole/g or less is used in order to provide a resin with sufficient thermal decoloration resistance and mechanical strength (refer to, for example, Japanese Unexamined Publication No. H9-3211, page 1 to page 4). In order to improve the reflectance by blending titanium oxide, it is preferable to increase the coating amount of a hydrous oxide and/or an oxide of a metal, for example, silica-alumina on the surface of titanium oxide particles (the base amount becomes 20 μmole/g or more). However, when commercially available titanium oxide particles with a large coating amount of silica-alumina were used directly, there was a phenomenon of lowering of the thermal stability in residence, that is, there was a limit in the improvement of thermal stability in residence by using only the method described above, wherein the titanium oxide was coated with a reactive silicone in advance.